Re: [photo-3d] slides from negatives?

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

----- Original Message -----
From: "Michael Galazin" <rexlion22@xxxxxxxxxxxxx>
To: "P3D mail list" <photo-3d@xxxxxxxxxxxxxxx>
Sent: Thursday, February 08, 2001 8:10 PM
Subject: [photo-3d] slides from negatives?


> Hi everyone,
>
> I've been wondering about something.  If you dupe a negative with more
> negative film, is the result a positive (e.g., a slide)?  I ask for 2
> reasons:
> 1] Sometimes I might shoot some negative film, then decide I'd like to
make
> a slide of a particular image.
> 2] Much has been said recently about negative film's superiority to slide
> film in some regards.  The point of loss is in making the print.  If a
slide
> could result by making a negative of a negative, I'm hypothesizing that
the
> resulting slide would be superior in those same respects to an ordinary
> slide (assuming a high quality duplicating lens).
>
> So, how about it?  What would one arrive at if duplicating negatives with
> more negative film?
>
> Best regards,
>
> Mike Galazin
>
>
> Shop online without a credit card
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> RocketCash, a NetZero subsidiary
>

Yes, you would get a positive.  However, I don't think that you would be
very pleased with it, unless you are looking for a special abstract effect.

Negative film has a red-orange filter layer that overlays the entire
negative.  Your final result would have this, and look muddy as well.  It
would also have a short scale like a slide, because this is a result of any
copy operation.

There is a film made specifically for making slides from negatives.  Kodak
calls it "Slide Print Film".  It is essentially a special negative film
without the red masking layer, but with an enhanced H & D curve to
compensate for the curve shape of the original negative film.  Large labs
specializing in copy work, as well as people who have home darkrooms, use
this for this exact purpose.

Actually, this is the way slide film itself works, except that it is on one
film that you don't have to copy.   All slide films are really two films in
one: both a negative, and a negative of that negative which is a positive.

Originally, slide film developing was a very lengthy process.  You would
first develop the negative, then fix this, then expose the film to a white
"reversal" light, which essentially "printed" the second negative [positive
layer(s)].  The first negative was then bleached out and the second negative
(called the positive because of the appearance of the image) was developed
and fixed.  All this, with wash cycles between each step.  Often over an
hour to process one roll of film.

Today, the film and processing are technically the same, but much shorter,
because several of the chemicals are combined so that several of the
individual steps are done simultaneously (Bleach and Fix are now Bleach-Fix,
or "Blix").  Even the reversal exposure is eliminated.  Oh, it is still
there, but it is done chemically rather than by actually using a light.

Your slide film has just as much tonal scale as negative film when it is
exposed in your camera and for the first part of the process.  In fact, if
you were to stop the process and fix the film after the first developer, you
would have a negative.

However, as soon as you complete the process, you are essentially making a
copy (a negative of a negative).  Therefore the result is a positive slide
with a shorter scale than the original negative, just as if you had copied a
negative film.  Anytime you make a copy the gamma goes up, the result is
contrastier, and the scale is shorter.  This is true whether your copy is on
the same piece of film (slide film) or a separate piece of film printed from
a separate negative(paper prints, or film prints - which we call slides).

Unfortunately, you can't get something for nothing.

JR